The grades on a math midterm at Loyola are normally distributed with $\mu = 71$ and $\sigma = 5.5$. Kevin earned a $64$ on the exam. Find the z-score for Kevin's exam grade. Round to two decimal places.
A z-score is defined as the number of standard deviations a specific point is away from the mean We can calculate the z-score for Kevin's exam grade by subtracting the mean $(\mu)$ from his grade and then dividing by the standard deviation $(\sigma)$ $ { z = \dfrac{x - {\mu}}{{\sigma}}} $ $ { z = \dfrac{64 - {71}}{{5.5}}} $ ${ z \approx -1.27}$ The z-score is $-1.27$. In other words, Kevin's score was $1.27$ standard deviations below the mean.